In many fields of the packaging industry, such as pet food, stock feed, seeds, etc., multi-wall gusseted paper bags are heavily used. Producers can choose from manual baggers, semi-automatic baggers or fully automated baggers. Baggers are understood to comprise at least some of the following subsystems: a bag magazine, a bag dispenser, a bag placer, a filling spout, an exit unit, a bag reshaper and a sealer. A bagger may or may not include a closing system.
No matter the type of bagger used, the bagging operation for the previously mentioned types of product is similar. On semi-automatic and fully automatic baggers, the bag dispenser places the bag on the filling spout, whereas manual baggers require the action of an operator to place a bag on the spout.
On automatic baggers, the gussets or the side folds of the bag are preferably maintained closed (in their original shape when the bag is empty and flat) while the bag is on the spout. Otherwise, a system has to reshape them. Reshaping is understood to be the action of bringing the flaps of the top of the bag together and re-folding the gussets or the side folds of the bag. While the shape of the top portion of the bag is being maintained thoroughly, the bag is then removed from the spout and transferred to the closing system. For manual and semi-automatic baggers, reshaping systems on the spout would be useless since they release the bag from the spout and let it fall on a conveyor, losing control of the bag shape. Therefore, the use of a system reshaping the gussets or side folds while the bag travels towards the closing system (called in-line reshaping system) is necessary, otherwise an operator needs to reshape the top of the bag and transfer it to the closing system. Correctly shaped gussets or side folds improve closing quality, bag appearance and produce bags that are easier to palletize.
Several criteria must be taken into account when searching for the more suitable bagger for the very precise needs of a typical application. Undoubtedly, any factory manager will opt for the best solution at the lowest price. The most important criteria are certainly the cost of the machine, its reliability, productivity, complexity, footprint and modularity (retrofitable), the safety related to the machine and the quality of the result (finished bag).
Manual baggers are the least expensive to purchase; however they are often associated with recurring costs such as operator salaries and insurance. The quality of the finished product is average to good, but it can be affected by different factors, such as operator exhaustion and lack of time to readjust the fold since the machine keeps running at a fixed pace. Manual baggers are more suitable for production rates around 15 to 20 bags per minute. As for manual baggers safety issues, operators' safety and ergonomics must be taken into account. On the other hand, they use minimal floor space.
Semi-automatic baggers are more expensive to purchase (around 2 to 3 times more expensive than the manual baggers). The bag reshaping quality is average to low since the spout is fixed and the bag falls from the spout, resulting in no bag control and hand-reformed bags. As with the manual baggers, the bag is reshaped by an operator who can be subject to the same factors expressed for manual baggers. Semi-automatic baggers can also reach an average productivity rate of 15 to 20 bags per minute. They can be retrofitted with in-line reshaping systems which automate the reshaping of the bag while it travels toward the closing system. In-line reshaping systems are quite expensive (it can cost the amount of the semi-automatic bagger itself) and give low quality results. As for reliability issues, due to their complex mechanical construction, these systems have an average to low mechanical reliability.
Fully automated baggers are the most expensive systems to purchase (around 4 to 6 times more expensive than the manual baggers). Large producers can afford this kind of machine which offers even more benefits to producers bagging large batches and high value end product. Automatic systems can reach an average productivity rate of 20 to 30 bags per minute. These fully automated baggers have quite complex mechanical systems and use more floor space than manual or semi-automatic baggers.
The most effective solution is obviously the completely automated bagger, but this option is also the most expensive and, for that reason, is not affordable and suitable for the majority of producers which must turn towards manual or semi-automatic systems. The manual and semi-automatic baggers are cheaper to purchase and can be retrofitted with an in-line reshaping system, but still, they will operate with limited productivity and quality. Considering the proportion of producers who use manual and semi-automatic baggers and those who increment their system with additional automation, it represents a large potential for machine sales.
The critical point is the system transferring the bag from the bagger to the closing system since it influences the bagger productivity and the quality of the finished product. The use of dedicated in-line reshaping systems increase bagger productivity, but decrease the quality of the product. Up to now, in the targeted fields such as pet food, stock feed, seeds, etc., of the packaging industry, there appears to be no small, low cost, high quality, high productivity, reliable, retrofitable system available capable of maintaining the shape of the top portion of the bag, transferring and transporting the bag from the bagger to a closing system. Hereinbelow, it is understood that the term “transport” encompasses a displacement of an item while properly supporting its weight during the displacement. The term “displacing” encompasses a displacement of an item between a point A and a point B. The term “transferring” encompasses a transfer and passage of an item between a first system carrying out operations on the item and a second system carrying out operations on the item
Some references show reshaping systems positioned on the machine spout. It would be possible for someone, well educated in this technical field and aware of prior art, to logically think of a system capable of taking the bag while it is being closed and maintaining its state until the closing of the bag is completed. A dedicated mechanical system would be quite easy to develop but would be cumbersome, hardly retrofitable, complex and expensive. The final solution would be very close to the existing automated baggers but with the disadvantages of having two machines not well integrated and almost as much expensive.
Another way of transferring the bag once it has been reshaped on the spout would be to use a robot to maintain the bag reshaped and transport it to the closing system. A robot capable of supporting the filled bag weight and moving it at the requested speed to achieve acceptable production rates (20 bags per minute minimum) would be too large to be well integrated on an existing bagger and would cost as much as an automated bagger. There are existing applications, frequently used in valve bagging applications, where a robot manipulates a filled bag from the bagger to the closing system, but this has never been done to be suitable for gusseted open mouth bags and sewing systems. These applications typically use a big six-axis robot.
Therefore, there is still a need for a system to automate manual and semi-automatic baggers, thereby improving their productivity and the quality of the finished bags. The preferable solution would be a small, low cost, high quality, high productivity, reliable, retrofittable system to maintain the shape of the top of the bag, while transporting and transferring the bag from the bagger to a closing system.